Flame-retardant impact modifier

ABSTRACT

In an example, a material includes a cellulosic nanomaterial and multiple polymer chains chemically bonded to the cellulosic nanomaterial. Each polymer chain includes a styrene-butadiene copolymer.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of co-pending U.S. patent applicationSer. No. 15/181,963, filed Jun. 14, 2016. The aforementioned relatedpatent application is herein incorporated by reference in its entirety.

I. FIELD OF THE DISCLOSURE

The present disclosure relates generally to flame-retardant impactmodifiers (e.g., for blending with a polymer).

II. BACKGROUND

Plastics are commonly derived from petrochemicals, resulting in pricefluctuations and supply chain instability. Replacing non-renewablepetroleum-based polymers with polymers derived from renewable resourcesmay be desirable. However, in certain contexts, there are limitedalternatives to petroleum-based polymers. To illustrate, particularrenewable polymers may have less than desirable material properties,such as low impact resistance or flame resistance. Such materialproperties can sometimes be improved by blending the polymers withadditive compounds. The additive compounds generally include otherpolymers. If the additive compounds are not from renewable sources,blending renewable polymers with the additive compounds reduces theportion of non-renewable petroleum-based polymers replaced with polymersderived from renewable resources.

III. SUMMARY OF THE DISCLOSURE

According to an embodiment, a renewable material can be used as anadditive to other polymers, especially other renewable polymers. Whenblended with another polymer, the renewable material improves impactresistance of the blend. Further, in some embodiments, the renewablematerial improves other material properties of the blend. For example,the renewable material may include flame retardant functional groupswhich may increase the flame retardancy or flame quenching properties ofthe blend. Additionally, the renewable material may include a rheologymodifier, which may improve rheological properties of the blend.

In a particular embodiment, a material (e.g., a polymer blend additive)includes a cellulosic nanomaterial and multiple polymer chainschemically bonded to the cellulosic nanomaterial. Each polymer chainincludes a styrene-butadiene copolymer.

In another embodiment, a polymer blend includes at least one polymer andan impact modifier blended with the at least one polymer. The impactmodifier includes a cellulosic nanomaterial and multiple polymer chainschemically bonded to the cellulosic nanomaterial. Each polymer chainincludes a styrene-butadiene copolymer.

In another embodiment, a method includes combining a methylmethacrylate-functionalized cellulosic nanomaterial with at least afirst monomer and a second monomer. The method also includes initiatinga reaction of the methyl methacrylate-functionalized cellulosicnanomaterial, the first monomer and the second monomer to form areactant including multiple polymer chains chemically bonded to themethyl methacrylate-functionalized cellulosic nanomaterial.

A renewable polymer blend additive can be used to improve materialproperties of other polymers. The renewable polymer blend additive maybe especially useful when blended with renewable polymers to maintain anoverall percentage of renewables in a final product. The renewablepolymer blend additive may enable use of renewable polymers incircumstances where non-renewable polymers may otherwise be used due toinability of renewable polymers to satisfy specified materialproperties, such as impact resistance, flame retardance, etc.

IV. BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a chemical reaction diagram illustrating a particularembodiment of preparation of a methyl methacrylate-functionalizedcellulosic nanomaterial;

FIG. 2 is a chemical reaction diagram illustrating a particularembodiment of preparation of an impact modifier compound;

FIG. 3 is a chemical reaction diagram illustrating a particularembodiment of preparation of a flame-retardant impact modifier compound;

FIG. 4 is a chemical reaction diagram illustrating another particularembodiment of preparation of a flame-retardant impact modifier compound;

FIG. 5 is a chemical reaction diagram illustrating another particularembodiment of preparation of a flame-retardant impact modifier compound;and

FIG. 6 is a flow diagram illustrating a particular embodiment of amethod of forming an impact modifier compound.

V. DETAILED DESCRIPTION

The present disclosure relates to polymeric materials, especiallyrenewable polymers. One hurdle in the use of renewable polymers in someindustries is that many renewable polymers tend to have unsatisfactoryignition resistance characteristics. One approach that is used toaddress this concern is to blend a renewable polymer with anothermaterial (e.g., a filler) that has flame retardant properties. In somecases, such fillers may include relatively small molecules in the formof particles. In such cases, to provide adequate flame retardance,loading levels of these flame retardant fillers can run as high as 30%.Such high loading levels can compromise mechanical properties of theresulting polymer blend. For example, the impact resistance, tensilestrength, modulus, or other properties of such a polymer blend may beunsatisfactory.

Thus, for some bio-derived or renewable polymers, adding a filler toimprove a polymer blend's mechanical properties (such as impactresistance) may degrade the polymer blend's ignition resistance.Additionally, adding a filler to improve the polymer blend's ignitionresistance may degrade the polymer blend's mechanical properties.Embodiments disclosed herein provide a polymeric filler material thatimproves both mechanical properties and ignition resistance of a polymerblend. The polymeric filler material can be bio-derived or renewable.Accordingly, adding the polymeric filler material to a polymer blenddoes not decrease a percentage or proportion of renewable content of thepolymer blend.

In a particular example, the polymeric filler material incorporatesorthogonal functionality on an impact modifier to address shortcomingspresent in other filler materials. To illustrate, to form the polymericfiller material a cellulosic nanomaterial (such as a cellulosenanocrystal or cellulose nanofiber material) may be functionalized withmethyl methacrylate. The functionalized cellulosic nanomaterial may becopolymerized with constituent monomers to form astyrene-butadiene-based impact modifier material. In some examples, thepolymeric filler material may be rendered flame retardant bycopolymerizing the constituent monomers with small amounts of a monomerthat has flame retardant characteristics, such as an acrylic, styrenic,or otherwise vinylic monomers containing flame-quenching functionalities(e.g., phosphorus, halogens, etc.) and capable of polymerizing viaradical polymerization. The resulting flame-retardant impact modifiermay be blended with one or more polymers (e.g., bio-renewable polymers,such as polylactic acid (PLA), polycaprolactone (PCL), polyamide (PA),polyglycolic acid (PGA), polyhydroxybutyrate (PHB),polyhydroxyalkanoates (PHA), polyethylene terephtalate (PET),polypropylene (PP), polyethylene (PE), PLA/starch material (PSM),polycarbonate (PC), or a combination or copolymer thereof).

In some implementations, the polymeric filler material may be formed byfunctionalizing the cellulosic nanomaterial with methyl methacrylate vianucleophilic acyl substitution. For example, the cellulosic nanomaterialmay be reacted with an acyl halide (e.g., methacryloyl chloride), anacrylic acid (e.g., methacrylic acid), or an acrylic anhydride (e.g.,methacrylic anhydride). The methyl methacrylate-functionalizedcellulosic nanomaterial may be copolymerized with a mixture of styreneand butadiene. To make the resultant product flame retardant, a flameretardant monomer may also be copolymerized with the styrene, thebutadiene and the methyl methacrylate-functionalized cellulosicnanomaterial. The copolymerization may be initiated using a thermalinitiator, a UV initiator, or another radical polymerization initiator.After polymerization, the resultant product (e.g., a cellulosicnanomaterial impact modifier/filler with the flame retardant groupscoupled to poly(methyl methacrylate-co-styrene-co-butadiene)) may becompounded with a polymer or polymer blend.

In some implementations, the methyl methacrylate-functionalizedcellulosic nanomaterial may have unreacted hydroxyl groups (i.e.,hydroxyl groups of the cellulosic nanomaterial that were not replacedwith methyl methacrylate groups). In such implementations, rather than(or in addition to) blending, the cellulosic nanomaterial impactmodifier/filler may be reacted with a polymer, polymer blend, or one ormore monomers to covalently link the cellulosic nanomaterial impactmodifier/filler to the polymer, polymer blend or monomers via thepreviously unreacted hydroxyl groups.

FIG. 1 is a chemical reaction diagram 100 illustrating a particularembodiment of preparation of a methyl methacrylate-functionalizedcellulosic nanomaterial. As illustrated in FIG. 1, a cellulosicnanomaterial 102 may be reacted to form a methylmethacrylate-functionalized cellulosic nanomaterial 106. For example,the cellulosic nanomaterial 102 may undergo nucleophilic acylsubstitution when mixed with an acyl halide, such as methacryloylchloride 104. In other examples, the cellulosic nanomaterial 102 may bereacted with methacrylic acid or methacrylic anhydride to form themethyl methacrylate-functionalized cellulosic nanomaterial 106.

The cellulosic nanomaterial 102 may include or correspond to a cellulosenanocrystal, a cellulose nanofiber, or another cellulosic materialhaving a characteristic dimension (e.g., a length) on the order of ananometer (e.g., less than about 1000 nanometers, less than about 100nanometers, or less than about 10 nanometers). The cellulosicnanomaterial 102 may include a plurality of hydroxyl groups. During thereaction illustrated in FIG. 1, the oxygen of the hydroxyl group attacksthe acyl carbon. This nucleophilic attack may be promoted by a base or acatalyst, such as pyridine. After the nucleophilic attack, the halide(e.g., the Cl) is eliminated (e.g., leaves to potentially form HCl). Ifa catalyst such as pyridine is used the catalyst may also act as aproton scavenger, neutralizing the HCl and helping the reaction proceed.By controlling stoichiometric ratios of the acyl halide and thecellulosic nanomaterial 102, the reaction can be used to produce acellulosic nanomaterial with multiple methyl methacrylate functionalgroups, such as the illustrative methyl methacrylate-functionalizedcellulosic nanomaterial 106 of FIG. 1.

As described further below, the methyl methacrylate groups of the methylmethacrylate-functionalized cellulosic nanomaterial 106 may be used tomodify the cellulosic nanomaterial 102 to form an additive or fillerhaving particular properties, such as flame-retardance or impactresistance.

FIG. 2 is a chemical reaction diagram 200 illustrating a particularembodiment of preparation of a compound that may be used as an impactmodifier. As illustrated in FIG. 2, the methylmethacrylate-functionalized cellulosic nanomaterial 106 may be reactedwith a plurality of monomer compounds to form a material 206 (e.g., thecompound that can be used as an impact modifier). For example, asillustrated in FIG. 2, the monomer compounds may include a styrene 202(or another compound having a styrenic functional group) and butadiene204. In this example, the styrene 202 and butadiene 204 may react toform a plurality of polymer chains, such as a first polymer chain 208and a second polymer chain 210. In the example of FIG. 2, each polymerchain 208, 210 includes a copolymer of styrene 202 and butadiene 204(e.g., polybutadiene-styrene (PBS)).

The polymer chains 208, 210 are chemically bonded to the cellulosicnanomaterial 102 via the methyl methacrylate groups (e.g., each polymerchain 208, 210 is coupled to the cellulosic nanomaterial 102 via acorresponding methyl methacrylate group). Thus, the material 206includes the cellulosic nanomaterial 102 with multiple polymer chains208, 210 chemically bonded to the cellulosic nanomaterial 102 via themethyl methacrylate groups.

As described above, the polymer chains 208, 210 may include astyrene-butadiene copolymer. Styrene-butadiene copolymers tend to havegood impact resistance. Accordingly, the material 206 may be blendedwith another polymer (or set of polymers) as an additive to improveimpact resistance of the blended polymer(s). If the styrene 202, thebutadiene 204, and the cellulosic nanomaterial 102 are derived fromrenewable sources, the material 206 can be used as a renewable impactmodifier. Thus, blending the material 206 with another polymer causes aquantity of renewable content in a final product (including the otherpolymer and the material 206) to increase. Thus, as much of the material206 as desired to achieve particular impact resistance levels can beadded without negatively affecting the proportion of renewable contentin the final product.

Additionally, cellulosic nanomaterials, such as the cellulosicnanomaterial 102, are sometimes added to polymers to modify rheologycharacteristics of the polymers. Thus, the material 206 may be added toa polymer blend as a rheology modifier, as an impact modifier, or asboth a rheology modifier and an impact modifier. Using a single material(e.g., the material 206) as both a rheology modifier and an impactmodifier may reduce costs associated with formulating a polymer blend(e.g., by simplifying supply chain management, reducing a number or costof polymer additives, etc.).

FIG. 3 is a chemical reaction diagram 300 illustrating a particularembodiment of preparation of a compound that may be used as aflame-retardant impact modifier. As illustrated in FIG. 3, the methylmethacrylate-functionalized cellulosic nanomaterial 106 may be reactedwith a plurality of monomer compounds to form a material 304 (e.g., thecompound that can be used as a flame-retardant impact modifier). Forexample, as illustrated in FIG. 3, the monomer compounds may includestyrene 202 (or another compound having a styrenic functional group),butadiene 204, and a flame-retardant monomer 302. The flame-retardantmonomer 302 includes a compound that is capable of radicalpolymerization and that has a flame-retardant or a flame-quenchingfunctional group (FR). For example, the flame-retardant monomer 302 mayinclude an acrylic compound, a styrenic compound, or an otherwisevinylic compound, that has a flame-retardant or a flame-quenchingfunctional group. The flame-retardant or flame-quenching functionalgroup may include a phosphorous-based or halogen-based group. Specific,non-limiting, examples of flame-retardant monomers 302 are describedwith reference to FIGS. 4 and 5.

In the example of FIG. 3, the styrene 202, the butadiene 204, and theflame-retardant monomer 302 may react to form a plurality of polymerchains, such as a first polymer chain 306 and a second polymer chain308. Thus, each of the polymer chains 306, 308 includes a copolymer ofstyrene 202, butadiene 204, and the flame-retardant monomer 302. Thepolymer chains 306, 308 are chemically bonded to the cellulosicnanomaterial 102 via the methyl methacrylate groups (e.g., each polymerchain 306, 308 is coupled to the cellulosic nanomaterial 102 via acorresponding methyl methacrylate group). Thus, the material 304includes the cellulosic nanomaterial 102 with multiple flame-retardantand impact resistant polymer chains 306, 308 chemically bonded to thecellulosic nanomaterial 102 via the methyl methacrylate groups.

Flame retardant properties of the material 304 may be related to aquantity of the flame-retardant monomer 302 used in the reactionillustrated in FIG. 3. For example, reacting the styrene 202, thebutadiene 204, and the methyl methacrylate-functionalized cellulosicnanomaterial 106 with more of the flame-retardant monomer 302 may resultin the material 304 having more of the flame retardant functionalgroups, which may improve flame retardancy of the material 304.Conversely, reacting the styrene 202, the butadiene 204, and the methylmethacrylate-functionalized cellulosic nanomaterial 106 with less of theflame-retardant monomers 302 may result in the material 304 having fewerof the flame retardant functional groups, which may decrease flameretardancy of the material 304.

The material 304 may be blended with another polymer (or set ofpolymers) as an additive to improve impact resistance of the blendedpolymer(s), to improve flame retardancy of the blended polymer(s), tomodify rheological properties of the blended polymer(s), or acombination thereof. If the styrene 202, the butadiene 204, theflame-retardant monomers 302, and the cellulosic nanomaterial 102 arederived from renewable sources, the material 304 can be used as arenewable filler in the blended polymer(s). Thus, blending the material304 with another polymer causes a quantity of renewable content in afinal product (including the other polymer and the material 304) toincrease. Accordingly, as much of the material 304 as desired to achieveparticular impact resistance levels, particular flame retardancecharacteristics, or both, can be added without negatively affecting theproportion of renewable content in the final product. Using a singlematerial (e.g., the material 304) as a rheology modifier, an impactmodifier, and a flame retardance modifier may reduce costs associatedwith formulating a polymer blend (e.g., by simplifying supply chainmanagement, reducing a number or cost of polymer additives, etc.).

FIG. 4 is a chemical reaction diagram 400 illustrating anotherparticular embodiment of preparation of a flame-retardant impactmodifier compound. FIG. 4 illustrates a specific, non-limiting exampleof flame retardant monomers that can be used to form the flame-retardantimpact modifier compound. In FIG. 4, the methylmethacrylate-functionalized cellulosic nanomaterial 106 may be reactedwith the styrene 202 (or another compound having a styrenic functionalgroup), the butadiene 204, and a flame-retardant monomer or multipleflame retardant monomers. In FIG. 4, the flame retardant monomer(s)include 4-(diphenylphosphino)styrene 402, or a combination of4-(diphenylphosphino)styrene 402 and diphenyl(4-vinylphenyl)phosphineoxide 404.

In the example of FIG. 4, the styrene 202, the butadiene 204, and theflame-retardant monomer(s) may react to form a plurality of polymerchains, such as a first polymer chain 408 and a second polymer chain410. Thus, each of the polymer chains 408, 410 includes a copolymer ofstyrene 202, butadiene 204, and the flame-retardant monomer(s). Thepolymer chains 408, 410 are chemically bonded to the cellulosicnanomaterial 102 via the methyl methacrylate groups (e.g., each polymerchain 408, 410 is coupled to the cellulosic nanomaterial 102 via acorresponding methyl methacrylate group). Thus, the material 406includes the cellulosic nanomaterial 102 with multiple flame-retardantand impact resistant polymer chains 408, 410 chemically bonded to thecellulosic nanomaterial 102 via the methyl methacrylate groups.

Flame retardant properties of the material 406 may be related to aquantity of the flame-retardant monomer(s) used in the reactionillustrated in FIG. 4. For example, reacting the styrene 202, thebutadiene 204, and the methyl methacrylate-functionalized cellulosicnanomaterial 106 with more of the flame-retardant monomer(s) may resultin the material 406 having more of the flame retardant functionalgroups, which may improve flame retardancy of the material 406.Conversely, reacting the styrene 202, the butadiene 204, and the methylmethacrylate-functionalized cellulosic nanomaterial 106 with less of theflame-retardant monomer(s) may result in the material 406 having fewerof the flame retardant functional groups, which may decrease flameretardancy of the material 406.

The material 406 may be blended with another polymer (or set ofpolymers) as an additive to improve impact resistance of the blendedpolymer(s), to improve flame retardance of the blended polymer(s), tomodify rheological properties of the blended polymer(s), or acombination thereof. If the styrene 202, the butadiene 204, theflame-retardant monomer(s), and the cellulosic nanomaterial 102 arederived from renewable sources, the material 406 can be used as arenewable filler in the blended polymer(s). Thus, blending the material406 with another polymer causes a quantity of renewable content in afinal product (including the other polymer and the material 406) toincrease. Accordingly, as much of the material 406 as desired to achieveparticular impact resistance levels, particular flame retardancecharacteristics, or both, can be added without negatively affecting theproportion of renewable content in the final product. Using a singlematerial (e.g., the material 406) as a rheology modifier, an impactmodifier, and a flame retardance modifier may reduce costs associatedwith formulating a polymer blend (e.g., by simplifying supply chainmanagement, reducing a number or cost of polymer additives, etc.).

FIG. 5 is a chemical reaction diagram 500 illustrating anotherparticular embodiment of preparation of a flame-retardant impactmodifier compound. FIG. 5 illustrates another specific, non-limitingexample of a flame retardant monomer 502 that can be used to form theflame-retardant impact modifier compound. In FIG. 5, the methylmethacrylate-functionalized cellulosic nanomaterial 106 may be reactedwith the styrene 202 (or another compound having a styrenic functionalgroup), the butadiene 204, and the flame retardant monomer 502. In FIG.5, the flame retardant monomer 502 includes an acrylic monomer with aphosphorus-based flame retardant moiety.

In the example of FIG. 5, the styrene 202, the butadiene 204, and theflame-retardant monomer 502 may react to form a plurality of polymerchains, such as a first polymer chain 506 and a second polymer chain508. Thus, each of the polymer chains 506, 508 includes a copolymer ofstyrene 202, butadiene 204, and the flame-retardant monomer 502. Thepolymer chains 506, 508 are chemically bonded to the cellulosicnanomaterial 102 via the methyl methacrylate groups (e.g., each polymerchain 506, 508 is coupled to the cellulosic nanomaterial 102 via acorresponding methyl methacrylate group). Thus, the material 504includes the cellulosic nanomaterial 102 with multiple flame-retardantand impact resistant polymer chains 506, 508 chemically bonded to thecellulosic nanomaterial 102 via the methyl methacrylate groups.

Flame retardant properties of the material 504 may be related to aquantity of the flame-retardant monomer(s) used in the reactionillustrated in FIG. 4. For example, reacting the styrene 202, thebutadiene 204, and the methyl methacrylate-functionalized cellulosicnanomaterial 106 with more of the flame-retardant monomer 502 may resultin the material 504 having more of the flame retardant functionalgroups, which may improve flame retardancy of the material 504.Conversely, reacting the styrene 202, the butadiene 204, and the methylmethacrylate-functionalized cellulosic nanomaterial 106 with less of theflame-retardant monomer 502 may result in the material 504 having fewerof the flame retardant functional groups, which may decrease flameretardancy of the material 504.

The material 504 may be blended with another polymer (or set ofpolymers) as an additive to improve impact resistance of the blendedpolymer(s), to improve flame retardance of the blended polymer(s), tomodify rheological properties of the blended polymer(s), or acombination thereof. If the styrene 202, the butadiene 204, theflame-retardant monomer 502, and the cellulosic nanomaterial 102 arederived from renewable sources, the material 504 can be used as arenewable filler in the blended polymer(s). Thus, blending the material504 with another polymer causes a quantity of renewable content in afinal product (including the other polymer and the material 504) toincrease. Accordingly, as much of the material 504 as desired to achieveparticular impact resistance levels, particular flame retardancecharacteristics, or both, can be added without negatively affecting theproportion of renewable content in the final product. Using a singlematerial (e.g., the material 504) as a rheology modifier, an impactmodifier, and a flame retardance modifier may reduce costs associatedwith formulating a polymer blend (e.g., by simplifying supply chainmanagement, reducing a number or cost of polymer additives, etc.).

FIG. 6 is a flow diagram illustrating a particular embodiment of amethod 600 of forming an impact modifier compound. The method 600 may beused to form any one or more of the material 206 of FIG. 2, the material304 of FIG. 3, the material 406 of FIG. 4, or the material 504 of FIG.5. Alternatively or in addition, a portion of the method 600 may be usedto form the methyl methacrylate-functionalized cellulosic nanomaterial106 of FIG. 1.

The method 600 may include, at 602, combining an acyl halide (e.g.,methacryloyl chloride), an acrylic acid (e.g., methacrylic acid), or anacrylic anhydride (e.g., methacrylic anhydride) with a cellulosicnanomaterial. For example, as illustrated in FIG. 1, the methacryloylchloride 104 may be combined with the cellulosic nanomaterial 102. Themethod 600 may also include, at 604, initiating a reaction to form amethyl methacrylate-functionalized cellulosic nanomaterial. For example,the acyl halide, the acrylic acid, or the acrylic anhydride may reactwith the cellulosic nanomaterial to form the methylmethacrylate-functionalized cellulosic nanomaterial 106 of FIG. 1. Insome examples, rather than forming the methylmethacrylate-functionalized cellulosic nanomaterial via reaction of thecellulosic nanomaterial with one or more reagents, the methylmethacrylate-functionalized cellulosic nanomaterial may be obtained viaan alternate mechanism, such as purchased as a reagent compound for usein forming an impact modifier.

The method 600 includes, at 606, combining the methylmethacrylate-functionalized cellulosic nanomaterial with at least afirst monomer and a second monomer. For example, the methylmethacrylate-functionalized cellulosic nanomaterial 106 may be combinedwith styrene, butadiene, one or more other radical polymerizablemonomers, or a combination thereof. In some embodiments, the monomersmay include an acrylic compound, a styrenic compound, or an otherwisevinylic compound, that has a flame-retardant or flame-quenchingfunctional group.

The method 600 also includes, at 608, initiating a reaction (e.g., aradical polymerization reaction) of the methylmethacrylate-functionalized cellulosic nanomaterial, the first monomerand the second monomer to form a compound including multiple polymerchains chemically bonded to the methyl methacrylate-functionalizedcellulosic nanomaterial. For example, as described with reference toFIG. 2, the methyl methacrylate-functionalized cellulosic nanomaterial106, the styrene 202 and the butadiene 204 may be reacted to form thematerial 206, which includes multiple polymer chains 208, 210 chemicallybonded to the methyl methacrylate-functionalized cellulosicnanomaterial. As another example, as described with reference to FIG. 3,the methyl methacrylate-functionalized cellulosic nanomaterial 106, thestyrene 202, the butadiene 204, and the flame-retardant monomer 302 maybe reacted to form the material 304, which includes multiple polymerchains 306, 308 chemically bonded to the methylmethacrylate-functionalized cellulosic nanomaterial. Additional examplesare described with reference to FIGS. 4 and 5.

In some embodiments, the method 600 may also include blending thecompound including multiple polymer chains chemically bonded to themethyl methacrylate-functionalized cellulosic nanomaterial (e.g., thematerial 206, the material 304, the material 406, or the material 504)with one or more base polymers to form a polymer blend. In suchembodiments, the compound may function as a filler for the polymerblend. The filler may modify rheological characteristics of polymerblends relative to the base polymer(s). Alternatively, or in addition,the filler may modify impact resistance characteristics of polymerblends relative to the base polymer(s). Alternatively, or in addition,the filler may modify fire-retardant characteristics of polymer blendsrelative to the base polymer(s). In particular embodiments, reactantsused to form the filler can be renewable (e.g., biologically derived).In such embodiments, adding the filler to the polymer blend may improvecharacteristics of the polymer blend without decreasing a proportion ofrenewable materials in the polymer blend.

The previous description of the disclosed embodiments is provided toenable any person skilled in the art to make or use the disclosedembodiments. Various modifications to these embodiments will be readilyapparent to those skilled in the art, and the generic principles definedherein may be applied to other embodiments without departing from thescope of the disclosure. Thus, the present disclosure is not intended tobe limited to the embodiments shown herein but is to be accorded thewidest scope possible consistent with the principles and features asdefined by the following claims.

1. A material comprising a cellulosic nanomaterial; and multiple polymerchains chemically bonded to the cellulosic nanomaterial, each polymerchain comprising a copolymer of styrene, butadiene, and a fire-retardantmonomer.
 2. The material of claim 1, wherein the fire-retardant monomercomprises a methyl methacrylate group.
 3. The material of claim 1,wherein the fire-retardant monomer is a halogen-containing compound. 4.The material of claim 1, wherein the fire-retardant monomer is aphosphorus-containing compound.
 5. The material of claim 1, wherein atleast one of the polymer chains comprises 4-(diphenylphosphino)styrene.6. The material of claim 1, wherein at least one of the polymer chainscomprises at least one of a phosphorus-containing acrylic monomer or aphosphorus-containing styrenic monomer.
 7. A polymer blend comprising:at least one polymer; an impact modifier blended with the at least onepolymer, the impact modifier comprising: a cellulosic nanomaterial; andmultiple polymer chains chemically bonded to the cellulosicnanomaterial, each polymer chain comprising a copolymer of styrene,butadiene, and a fire-retardant monomer.
 8. The polymer blend of claim7, wherein the fire-retardant monomer comprises a methyl methacrylategroup.
 9. The polymer blend of claim 7, wherein the fire-retardantmonomer comprises a halogen-containing compound.
 10. The polymer blendof claim 7, wherein the fire-retardant monomer comprises at least one ofa phosphorus-containing acrylic monomer or a phosphorus-containingstyrenic monomer.
 11. The polymer blend of claim 7, wherein the at leastone polymer comprises a bio-renewable polymer.
 12. The polymer blend ofclaim 7, wherein the at least one polymer comprises polylactic acid(PLA), polycaprolactone (PCL), polyamide (PA), polyglycolic acid (PGA),polyhydroxybutyrate (PHB), polyhydroxyalkanoates (PHA), polyethyleneterephtalate (PET), polypropylene (PP), polyethylene (PE), plastarchmaterial (PSM), polycarbonate (PC), or a combination or copolymerthereof.
 13. A method comprising combining a methylmethacrylate-functionalized cellulosic nanomaterial with at least astyrenic first monomer and a second monomer; and initiating a reactionof the methyl methacrylate-functionalized cellulosic nanomaterial, thefirst monomer and the second monomer to form a compound includingmultiple polymer chains chemically bonded to the methylmethacrylate-functionalized cellulosic nanomaterial.
 14. The method ofclaim 13, further comprising, before combining the methylmethacrylate-functionalized cellulosic nanomaterial with at least thefirst monomer and the second monomer: combining an acyl halide and acellulosic nanomaterial; and initiating a reaction of the acyl halideand the cellulosic nanomaterial to form the methylmethacrylate-functionalized cellulosic nanomaterial.
 15. The method ofclaim 13, wherein the first monomer includes styrene and the secondmonomer includes butadiene.
 16. The method of claim 13, wherein afire-retardant compound is combined with the methylmethacrylate-functionalized cellulosic nanomaterial, the first monomer,and the second monomer, and at least one of the polymer chains includesthe fire-retardant compound.